Isolation and Elucidation of Structures of Biologically Active Secondary Metabolites from Various Organisms, Including Cyanobacteria, Sponges, and Areca catechu.

Abstract

Investigation of extracts of several biological specimens, including cyanobacteria, sponges and Areca nut, for activity in various biological assays led to the isolation of several known and new secondary metabolites. Sesquiterpene quinones and hydroquinones isolated from the sponge Dactylospongia elegans Thiele (Thorectidae) showed strong to moderate cytotoxicity (CC50 between 2.4 and 22.6 μM) against human glioblastoma (U251MG) and human pancreatic carcinoma (Panc-1) cell lines. Furthermore, ilimaquinone (IC50 65 μM) and smenospongine (IC50 78 μM) exhibited moderate inhibition of BACE1, an enzyme implicated in the pathogenesis of Alzheimer’s disease. The aqueous fractions of the extracts of Areca catechu L. (Arecaceae) displayed Ca-signaling effects in immune (Jurkat, U937 and RBL-2H3) cell lines and the components responsible for this activity may be oligomeric or polymeric flavonoids. The utility of prediction of 1H and 13C NMR chemical shifts using density functional theory computations was demonstrated in the elucidation of structures of three new molecules.